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Hydration for Running in Hot Weather

Are you running in the summer? Knowing about hydration for running in hot weather can help keep you hydrated, fueled, and improve your performance.

This blog post is meant for informational purposes only and is not diagnostic criteria and should not be construed as medical advise. Please speak to your medical care provider for prescriptive advice.

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Now that the warmer weather is here to stay, one of the things I talk to my athletes about is summer hydration aka how much water you should drink when training in the summer! 

Hydration for runners in the summer months can be so challenging, especially if you’re a salty sweater runner.

So, these are things I’m always discussing with my runners, whether you’re looking for tips for nutrition during the marathon, half marathon recovery or just beginning tips for how much water should a runner drink.

How to stay hydrated in the summer while running is a huge challenge, so this article will help address the main concerns.

While hydration is important any time you run and exercise, it’s EXTRA important in the summer months.

Here’s a great guide on hydration for runners in general. 

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Why Hydration for Runners Matters

When determining how much water to drink before a run, you have to keep a few things in mind.

Our bodies want to seek equilibrium and will do everything possible to do so.

When talking about hydration for runners, it’s firstly important to understand what water balance is.

homemade watermelon electrolyte drink with lemon and salt
Making your own electrolyte drink is a great way to avoid dehydration and handle gut issues.

Our bodies achieve water balance when our intake of fluids (and some foods) is equivalent to the water we lose, which is mainly through urine, sweat and feces.

On the other hand, we become dehydrated when we lose that water balance, and our fluid losses are greater than fluid intake. 

Therefore, our bodies aren’t able to cool themselves during exercise.

Dehydration can have lasting effects on performance including:

  • slowed delivery of nutrients and oxygen to cells
  • altered body temperature
  • increased muscle cramps
  • decreased cognitive function and concentration 
  • and much more
How much water should you drink in the summer months when running?

Did you know it can take up to 24 hours for the body to regain fluid balance after dehydration?!

Therefore, staying hydrated in the summer heat, perhaps through the use of a proper hydration pack for running will improve performance and keep you safe.

How Much Water Should a Runner Drink?

Now that we know how important hydration is, how much should you drink before running?

Well, like much of nutrition, it varies and is very personalized.

Athletes, and those who are active, generally need more than the general recommendation of 8 cups a day.

Comparing hydration for a master’s athlete and hydration in teenage athletes is a little different.

Generally speaking, half of your body weight, in ounces, is a pretty good estimation but doesn’t account for exercise – especially outdoor exercise in the heat.

pitcher and glass of water

Fluid needs vary per person and activity level.

Needs are higher in heat and humidity, travel, altitude, illness and during intense training cycles. 

If you drink high amounts of caffeine before a race, you want to make sure you’re drinking enough water to achieve thermal regulation and fluid balance. 

Oftentimes, these homemade electrolyte drinks can help, plus they taste fresh and delicious. Hydration doesn’t have to be JUST water alone.

The best way to manage hydration is to focus on it before, during and after activity. Once you lose water balance or become dehydrated, it’s nearly impossible to catch up during exercise.

Thomas DT, Erdman KA, Burke LM. Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance. J Acad Nutr Diet. 2016 Mar;116(3):501-528. doi: 10.1016/j.jand.2015.12.006. Erratum in: J Acad Nutr Diet. 2017 Jan;117(1):146. PMID: 26920240.

How Much Water to Drink Before a Run 

A general recommendation is to consume 8 ounces of fluid 15 to 30 minutes before exercise and upwards of 16 ounces a few hours prior.

During training, you want to drink to prevent thirst.

You also want to try to prevent a greater than 2 percent loss of body weight.

While individual needs vary, a good starting point is 0.4 to 0.8 liters per hour. You can view this half marathon hydration guide for more tips.

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What to Wear for Summer Running

Did you know that what you wear can affect your sweat and how quickly your body heats up?

You want to wear breathable fabrics! Check out this post with options about what to wear running in summer.

How Much Water To Drink After Exercise

After exercise, drink 16 to 24 ounces of water for every pound lost. Staying hydrated isn’t just about water though – remember those electrolytes!

I love maple water for just this reason – it’s tasty and hydrating – it can also benefit endurance runners!

Including sodium in fluids and foods can also help with fluid retention.

drink simple maple water carton in front of a pair of orange running shoes

Chia seeds can especially be very hydrating, like this chocolate cherry chia pudding or chia banana pudding

And if you’re breastfeeding after running, liquids are even more important to keep your supply up!

Dairy products (looking at you, chocolate milk) are great post-workout options with sufficient carbohydrates, protein and electrolytes.

Bread, soup and a couple of scrambled eggs will also give you some sodium, if you prefer real foods.

Bananas, potatoes and avocados are great sources of potassium, which are necessary, as electrolytes after running can make a big difference with rehydration.

How much water should you drink in the summer months when running?

How to Moniter Summer Hyration

Staying on top of your hydration, especially in the summer months, is so important.

The average person sweats between 0.3 and 2.4 liters per hour during exercise.

Obviously, as in hydration needs, there is a large individual variability in terms of sweat loss rates.

Sweat loss is influenced by genetics, gender, age, temperature, exercise intensity, fitness level and acclimatization.

Unless you have the ability to perform a sweat rate test, there are some other things you can do to stay on top of your hydration levels.

All of these are important to monitor for these summer hydration for running.

Check Your Urine

Urine that is darker in color and low in volume is indicative of dehydration.

Aim for a light-colored urine at regular intervals to gauge your hydration status.

I love using this chart with clients. Your pee shouldn’t be clear, or too concentrated (like apple juice).

You want it more like a lemonade color.

urine chart for dehydration

Weigh Yourself Before And After Exercise

While I’m normally not much of a fan of weighing yourself to measure health, when talking about hydration status, it can be helpful for some people who struggle with staying hydrated, depending on the situation.

I also wouldn’t recommend this to anyone with an eating disorder or disordered eating history. 

If you weigh yourself before/after a run, each pound of weight lost is equivalent to about 16 ounces of fluid lost.

You want to replenish that amount of liquid plus 125 to 150 percent more to achieve optimal hydration, since sweat and urine losses continue after exercise.

So, if you lost one pound of weight after a training session, aim for 24 ounces of water to achieve “re-hydration.”

man using primo water system and filling glass up with water

If you fall into the above categories, I would recommend focusing on drinking enough before and during exercise.

It’s also important to replenish after with a combination of water (or other liquids), electrolytes and an adequate post-exercise meal.

For optimal performance, avoid losing more than 2-3% of your body weight during exercise. This equals about 3-4 lbs for a 150-pound athlete.

To calculate your body weight loss percentage, take your weight before exercise – weight after exercise/weight before exercise.

Then, you’ll calculate that number as a percentage.

In short, fluid needs vary per person and activity level, and are higher in heat and humidity, travel, altitude, illness and during intense training cycles. 

woman drinking water before running

Watch Your Sweat (Is it Salty?)

If your sweat is salty, it likely contains a high concentration of sodium and you may be a “salty sweater.”

If this is the case, you’ll want to consume more sodium-containing food and beverages before, during and after prolonged exercise to manage your hydration status.

This pasta bake and chicken stir fry are great for after exercise.

You can even add salt to pre/post food options, like salted cinnamon peanut butter on dates!

Cinnamon peanut butter is a creamy, tasty peanut butter made in your own kitchen with only natural ingredients!  If you've never tried peanut butter and cinnamon together, you're in for a real treat!

Consume Water And Electrolytes

As I mentioned above, while drinking water is important, it’s not the ONLY answer for hydration.

Drinking water without consuming sufficient electrolytes can lead to serious consequences, such as hyponatremia, or a low concentration of sodium in relation to water.

Increasing sodium levels through electrolyte consumption can help your body retain fluids while helping you feel thirsty. 

An adequate sodium intake will also decrease your sweat rate, therefore decreasing the amount of water lost in sweat.

Most intense athletes don’t need to monitor the sodium in their daily lives.

See more about electrolytes for runners, and specifically, magnesium for runners.

Nuun tub and skratch electrolyte packets

Proper Hydration for Running in the Heat

Summer hydration tips revolve around preparation and drinking enough water on rest days, too.

And remember, summer hydration smoothies can be a great way to prevent taste fatigue and add in other nutrients and calories, too. 

If you’re struggling with running and hydration, here are some other tips for running hydration: 

  • Carry a water bottle at all times, drink water at meals and incorporate ample fruits and vegetables with a higher water content in your diet. My favorites are cucumbers, watermelon, strawberries and oranges.
  • Add powders or electrolytes to your water. My favorites are UCAN hydrate powder and NUUN tabs.
  • While sports drinks can also provide ample electrolytes, your everyday liquids (like milk, juice and even pregnancy mocktails) can supplement, as well. I also love using huma plus gels or honey stingers for longer runs to get both carbs + electrolytes.
  • Drink when you’re thirsty, but be prepared to follow a “loose plan” too – i.e. – drink 10-20 oz/water, or something you come up with based on your sweat rate, nutrition plan and distance.
running belts with running gels and fuel on hardwood floor

Like I tell my athletes, you can do all the training and run all the miles.

But, if you don’t have your nutrition and hydration plan down, you won’t optimize your performance!

If you want more tips on avoiding dehydration in winter and crafting your winter running plan, check out the post I wrote on that. 

Hydration is a very complicated topic and is so individual.

We have a whole module that talks more about developing your hydration and electrolyte plan for endurance exercise in our Nail your Nutrition Course that helps with determining your needs and what to change or modify.

Other race day posts:

References:

  • Bean, A. (2022). The Complete Guide to Sports Nutrition. Bloomsbury Sport. 
  • Belval LN, Hosokawa Y, Casa DJ, Adams WM, Armstrong LE, Baker LB, Burke L, Cheuvront S, Chiampas G, González-Alonso J, Huggins RA, Kavouras SA, Lee EC, McDermott BP, Miller K, Schlader Z, Sims S, Stearns RL, Troyanos C, Wingo J. Practical Hydration Solutions for Sports. Nutrients. 2019 Jul 9;11(7):1550. doi: 10.3390/nu11071550. PMID: 31324008; PMCID: PMC6682880.
  • Thomas DT, Erdman KA, Burke LM. Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance. J Acad Nutr Diet. 2016 Mar;116(3):501-528. doi: 10.1016/j.jand.2015.12.006. Erratum in: J Acad Nutr Diet. 2017 Jan;117(1):146. PMID: 26920240.
  • Vitale K, Getzin A. Nutrition and Supplement Update for the Endurance Athlete: Review and Recommendations. Nutrients. 2019; 11(6):1289. https://doi.org/10.3390/nu11061289
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  1. This is very timely info for summer running! On any given day, I do drink half of my body weight in ounces of water. I feel “icky” without my water intake. I’m a very heavy and salty sweater, which is probably a byproduct of running in the deep south. But, I find it a tricky situation not to drink too much. How do we know how much is too much? I’d like to hear your thoughts on that too. Thanks for linking!

  2. Very informative and helpful post! It’s incredible how much people sweat during summer runs, well, at least me for sure 🙂 I am always sure to drink a ton of NUUN and water afterwards but I don’t always do that great of a job DURING a run, so I’m catching up the rest of the day.

    Thanks for sharing!

  3. Great reminder! I am so surprised when runners I know do not actually even consider drinking extra in the summer! it doesn’t even get that hot here but STILL you need the extra hydration when the weather is warm and you are out in the sun sweating! I like to drink ice cold water do and generally get about 2 – 3 liters in per day. I don’t however drink too much before I go out (that’s why I really pre-hydrate) because, well, I’m almost 50 and so is my bladder, ifyouknowwhatImean… I also always take hydration with me on any run more than 1 hour and usually that would be in the form of my pack with two water flasks (minimum) with SiS or Nuun electrolyte tabs. I am loving Clif shot bloks too at the moment; they have a new flavor – salted watermelon! I’m a salty sweater and am now proudly going to tell my hubs that YES I will put extra salt on my food because I need it!

    1. I think that’s one of the more problematic situations – when people don’t drink extra, or may not feel extra thirsty. We are still losing the sweat, regardless! And salted watermelon sounds fabulous 🙂

  4. Great info! I ran a 5K recently on a very hot/humid day, and also ran 3 miles before the race. I weighed myself before and after…and I lost four pounds from all the sweating. I never felt faint or weird, but I definitely was a wet mess LOL

  5. As an elite runner, a (somewhat) new mom and someone who recovered from an eating disorder- I’m disappointed in this post. It seems like you are totally on board with intuitive eating/ movement and HAES until running comes into the picture. I guess I just dont see how telling people to weigh themselves before and after exercise in order to know how much water to drink is helpful. To me, that is rigid and unnecessary. Why not simply tell people to drink fluids before, during, after exercise and then move on with their day? I love your blog so much, but this post left me feeling unsure of your priorities/ where you stand.

    1. Hi Roalla – first off, thank you for reading and for your comment. I can completely see what you are saying and I guess I should have started by saying most of these are recommendations from the Academy of Sports Medicine and is research based – for some people who are exercising intensely or may not be in touch with their sweat rates or how much they are drinking, it may be one measure they could use. That being said, I went back in and added in my post that I wouldn’t recommend this for those recovering from eating disorders or disordered eating, or those struggling with body image who can get fixated on a number.

    1. Good question – that picture isn’t quite clear! I generally say clear is a little overhydrated, it should be a light yellow, but I’m sure it may vary slightly per person.

  6. Great information!!! I ran long on Saturday and I was certainly crusty. This summer is so different from any that I have trained in. I’m needing to get some salt tablets.

  7. This is such great info! I have been struggling with staying properly hydrated lately. Usually when i realize i’m dehydrated its too late. I have been good about hydrating after a run because i’m really thirsty! My husband is such a salty sweater-you can literally see the salt on his face after a run!

    1. I’ve been struggling myself in the summer and with breastfeeding. I need to remind myself to keep drinking, too!

  8. Thank you so so much for this! This is honestly so helpful. I find that I worry that I’m either drinking too little or too much water, so now I can figure out exactly how much I need!

    1. So glad you found it helpful, Samantha! It’s probably impossible to get it exactly right, but judging by feel can be good too!

  9. Love this! I noticed I was getting more tired on my runs than normal so I started bringing my water bottle with me and noticed a difference. It’s interesting how much water you can lose during a run. Now I’m super interested in that portion of it. Thanks for sharing Sarah!